Electrical condenser and process of assembly thereof



Oct. 20, 1931. s. s. .CRAMER 1,828,027

ELECTRICAL CONDENSER AND PROCESS OF ASSEMBLY THEREFOR Filed Feb. 27.1929 INVENTOR STANLEY s. CR/IMER Br %7 8T/ FIG. 7 I I ATTORNE PatentedOct. 20, 1931 UNITED STATES PATENT OFFICE STANLEY S. GRAMER, OF HADDONHEIGHTS, NEW JERSEY, ASSIGNOR TO RADIO CON- DENSER COMPANY, OF CAMDEN,NEW JERSEY ELECTRICAL CONDENSER AND PROCESS OF ASSEMBLY THEREOFApplication filed February 27, 1929. Serial No. 343,200.

This invention relates to improvements in electrical condensers of thevariable type such as are used in connection with tunable circuits ofradio apparatus, particularly the kind used for receiving purposes.

In the construction of such condensers, it is now quite customary toassemble a plurality of such condenser units comprising stator and rotorplates upon a common frame-work,

so that one control means such as a knob,

may serve to actuate all of the condensers simultaneously.

,Due to the fact that there are bound to be variations in themanufacture of each condenser making up the whole assembly and furtherdue to the fact that there are bound to be manufacturing differences inthe tuning coils and the circuits connecting these coils with thecondensers and other parts of the receiving'set, it becomes apparentthat the maximum resonance of each tunable circuit will not be obtainedfor each dial setting without the use of some compensating means wherebyeach individual condenser may be adjusted so as to bring all of thetunable circuits to substantially the maximum point on the resonancecurve of each circuit as the common dial is operated. Part of thistrouble is due to the fact that the initial capacity of each of thecondenser units is not what it should be, and therefore the condenser isoff on its resonance curve throughout the entire range of movement ofthe dial. It is therefore the principal object of my invention toprovide a construction in which these difliculties may be overcome or atleast reduced to a minimum, by providing ready means for changing theinitial capacity of each condenser and the slope of the resonance curve,and for compensating for inaccuracies in manufacture, etc.

Another object of my invention is to provide a condenser in which theleakage losses are reduced to a minimum. 1

Another object of my invention is to provide a process which willmaterially speed up the operation of assembly and which will assist inpositioning the separate stator groups so as to aid in the final settingof the condensers. Y

vention is applicable and to which I first applied the same.

Figure 4 is a side elevation of the form of.

condenser shown in Figure 3.

Figure 5 is a plan view showing certain details involved in the processof assembly of the complete condenser shown in Figure 1.

Figure 6 is an end View of Figure 5.

Figure 7 is a side elevation of Figure 5.

Figure 8 is a'fragmentary viewshowing a modified form of construction indetail.

' Figure 9 is a view similar to Figure 8,-but of a still furthermodified form.

Figure 10 is a detailed view of the stator -holding parts used inconnection with Figures 8 and 9.

Referring now to the details wherein like numbers refer to correspondingarts in the various views, 1 is a frame-work iaving end plates 2 and 3which may be fastened thereto in an satisfactory manner as by upset lugs4. the end plates 2 and in any satisfactory manner, but preferably inthe manner shown and described in my application S. N. 332,- 700, filedJanuary 15, 1929. The rotor shaft he rotor shaft 5 is carried between 5carries, on sleeves fastened to the shaft as set forth in saidapplication, a. plurality of rotor plates 6 tied together at their outerends b the tie bars 7.-

As s own in'Figure 1, the rotor plates are in a position slightly out offull engagement with their cooperating stator plates. These statorplates are shown at 8 through the openings 9- formed in the sides of theframe- 1. It is'to be understood that the rear side of the assembledcondenser is substantially the same as the front side shown in Figure 1.

The stator groups of plates have their oppo- 1 is positioned exterior tothese fingers.

Screws 20 pass-through the insulators 19 and 18 and through the spaces14 and-15 into the tie bar 10, thereby holding the stator in position inthe frame 1. The tie bars 10 on the stator group of plates arepreferably provided with a plurality of projections 21, three beingpreferably used in this size of condenser shown, and these projectionsare the parts of the tie bars 10 which make contact with the insulator18, whereby the surface contact of the tie bar is reduced to a verysmall area, thereby reducing the leakage losses of the stator throughthe frame-work to a minimum.

As shown in Figure 8, the side of the frame-work 1 is provided with apair of slots 22 through each of which, two of the stator plates 8 areshown. 'lhis construction has a finger 23 and between'the tie bar 10 andthis finger, and the sides of the slots 22, a bushing 24 (see Fig. 10)is positioned. This bushing 24 cooperating with the insulating washer25, acts to insulate the stator from the frame.

In Figure 9, oblong slots 26 are used in place of the open slots 22.

In the form of condenser shown in Figures 3 and 4, the frame 1 is a diecasting instead of a punched construction, as illustrated in Fi ure 1.As shown in Figure 3, a block 27 is fastened to the frame 1 by screws 28positioned in a channel portion of the frame, but it is to be understoodthat the block 27 may be made integral with the frame. In thisconstruction, as shown at the right-hand part of Figure 4, two slots 29corresponding with the slots 22 of Figure 8, are provided, but the samesort of insulators 18 and 19 as shown in Figure 2 are used to engage thetie bars 10, which are the same as in the constructions previouslydescribed. It is to be understoodthat in the form shown in Figures 1, 2,3, and 4, the widths of the slots 14, 15, and 29 are such as to provideconsiderable clearance for the screws 20, so that by loosening thescrews 20, say on one side of the frame, this end of the stator may beraised or lowered or moved laterallygto position the stator at anydesired point with respect to the rotor plates. Likewise, the oppositeside of each group of stator plates may be shifted, or the entire groupof stator plates may be shifted. This provides a construction which willattain the objects heretofore expressed. As shown 1n Figures 3 and 4, aspecial compensating means generally referred to by the numeral .30, isshown, but since this form is the subject matter of a separateapplication, it will these blocks are positioned on the base 31 atpoints corresponding to the proper location of the stator groups 8.

F astened by screw 34 to opposite sides and at oppositeends of the.blocks 32, are uprights 35. Each of the uprights 35 is provided with anotch 36 which is adapted to receive the tie bars 10 of the stators.Another notch 37 is provided to receive the insulator 18. In theassembly of the condenser, the

stator groups are placed on the blocks 32 so the tie bars enter thenotches 36. and then the frame-work 1 1s placed upside down over thestator'groups as shown by the dotted lines 38.

The insulators 18 are dropped into position in the grooves 37 and theinsulators 19 are then applied exterior to the lingers 11, 12, and 13,and the screws 20 inserted into position and tightened up, therebylocking the stator groups to the frame-work. The framework is thenturned right side up and the rotor groups of plates, previouslyassembled to their mounting sleeves, are placed in interleaved positionwith their respcctivestator groups of plates, and the shaft 5 is theninserted through the end plate 3 and the various sleeves of the rotorgroups, and into the end plate 2.

In the case of Figure 1, the bearing races may then be filled in themanner set forth in my copending application Serial No. 466,871, filedJuly 9, 1930. In the case of Figure 4, the shaft 5 is simply insertedthrough one pedestal of the frame and through the rotor sleeves into theother pedestal. In both cases, after the shafts and rotors have beenproperly positioned, the rotor sleeves are fastened to the shaft 5 byany suitable means as by set screws.

As has been explained, when the time comes to adjust each condenserint-he radio receiving set, the stator grou may be ad- 'usted as hasbeen described. It sometimes appens that in different sets due to thearrangement of the tuning coils and other anpa-rat-us, more or lessinitial capacity must be given each condenser, and to roughlyapindicated by the lines 39,- 40, 41, and 42,

As shown in the various figures,

which are shown in Figures 6 and 7. It will 'l n having end bearingsupports, a rotor and shaft carried by said end supports, spacedmetallic parts extending from theframe and located on opposite sides ofthe rotor shaft, a stator consisting'of a plurality of plates heldtogether at least in part by a tie bar across opposite ends of saidplates, an insulator between each tie plate and said spaced frame parts,an insulator on the opposite side of said spaced frame parts and screwsgoing through both said insulators and between said spaced frame partsinto the tie bars for adjustably, clamping the stator in position.

2. A compound condenser structure including; a frame having end bearingsupports, a shaft extending between said supports and carrying aplurality of rotors, a plurality of Y fingers formed in groups on saidframe opposite each rotor, a plurality of stators each consisting of aplurality of plates held together at least in part by a tie bar acrossopposite. ends of said plates, a pair of insulators for each statorembracing each of said finger groups, and screws going through each pairof insulators between the associated fingers into the associated statortiebars.

3. A condenserincluding a frame structure having end bearing supports, arotor and shaft carried by said end supports, at least one metallicportion formed by two slots in a part of the frame and located onopposite sides of the rotor shaft, a stator consisting of a plurality ofplates held together at least in Y part by a tie bar across oppositeends of said plates, screws passing through said slots into said tiebars, and insulators for receiving said screws and for insulating thetie bars and stator from the frame, said slots having dimensions so asto allow the stator to be adjusted up and down, laterally, as well asslightly oscillatory.

4. A compound condenser structure in cluding; a frame. having endbearing supports, a shaft extendingbetween said supports and carrying aplurality of rotors, at

least one portion formed by two slots in a part of the frame andlocatedon opposite sides of the rotor shaft, a plurality'of stators eachconsisting of a plurality of plates held together at least in part by atie bar across opposite ends of said plates, screws passing through saidslots into said, tie bars, and insulators for receiving said screws andfor insulating the tie bars and stators from the frame, said slotshaving dimensions so as to tween each tie plate and said spaced frameparts, an insulator on the opposite side of said spaced frame parts andscrews going" through both said insulators and between said spaced frameparts into the tie bars, for adj ustably clamping the stator inposition, and means for reducing the area of contact of'the tie barswith their respective insulators including a plurality of ,projectionsextending between each insulator and its associated tie bar for spacingone from the other.

6. A compound condenser structure including; a frame having end bearingsupports, a shaft extending between said supports and carrying aplurality of rotors, said frame on opposite sides of the rotor havingopenings punched therein forming a plurality of fingers, a group ofstator plates having their opposite ends anchored together by a tie bar,screws passing through said openings between the fingers into the tiebars, and

a pair of insulators for each tie bar disposedv on opposite sides of thefingers adjacent each tie bar to insulate the same from the frame, saidopening being sufiiciently lar e to allow the stators to be adjusted inthree (firections.

7. The process of assembly of a compound condenser including; aplurality of groups of stator and rotorplates having tie bars and aframe, which consists in provlding an assembly fixture having a basewith blocks spaced thereon of a width and length to support the statorgroups, said blocks having uprights on opposite sides and corners withnotches in ,tie bars, placing a group of rotor plates, previouslyassembled on their respective sleeves in interleaved position with thegroups of i stator plates, then inserting an operatin shaft' through oneend support and all of the rotor sleeves, into the other end sufpport,and

fastening said sleeves to said sha 8. The process of assembly of acompound condenser including; a plurality of groups of stator and rotorplates having tie bars and a frame, which consists in providing anassembly fixture having a base with quickly removable blocks spacedthereon of a width and length to support the stator groups and athickness to approximate the final adjustable position of the statorgroups, said blocks having uprights on opposite sides and corners withnotches in the uprights, placing said stator groups onto said blocks inreverse position so the tie bars thereof are positioned in a part'ofsaid notches, then placing the frame over the stator groups, placinginsulators into the other of said notches between the tie bars andframe, applying insulators to the exterior of the frame adjacent thefirst insulators, then applying holding means to the insulators and tiebars, placing a group of rotor plates, previously assembled on theirrespective sleeves, in interleaved position with the groups of statorplates, then inserting an operating shaft through'one end support andall of the rotor sleeves, into the other end support, and fastening saidsleeves to said shaft, and finally shifting one or more of the statorgroups to obtain the desired capacity curve of each individual condensercomprising the whole compound condenser.

In testimony whereof. I afiix my signature.

STANLEY S. CRAMER.

